Aspiring to become a rock star fitness guru, or just want to whip some people into shape? Better have some credentials: Few gyms hire trainers without at least one certification or training-specific degree, and most clients like the peace of mind that comes with those credentials. A degree in kinesiology is one way to start, but the most common route is to get certified.

Sounds simple, but choosing the correct certification can be just as daunting as the exam itself. In the U.S. alone, there are over 300 certifying organizations offering multiple types of tests, from individual and specialty classes to group training certificates.

Go Pro — The Need-to-Know

Though there’s historically little standardization in the personal training industry, the National Commission of Certifying Agencies (NCCA) eliminates some of the guesswork for certification in this and other fields. The NCCA maintains the accreditation standards for the nation’s training certification organizations. When an organization applies for certification, the NCCA works to ensure the examination process is fair and unbiased, the test measures the candidate’s minimal competence of the material, and the organization has the means to support its professionals.

Most certifying organizations have a few common prerequisites (even for the training prodigies out there): The test-taker must be at least 18 years old, have a high school diploma or equivalent, and be CPR certified. These prereqs may not seem limiting, but getting certified usually costs enough to require some serious thought. Ready to take the plunge for a new career (and dip into that pocket book)? Below are a few of the more prominent training certification organizations, along with their testing practices and associated costs:

• The American Council of Exercise (ACE) is the largest non-profit fitness certification, education, and training organization in the world with nearly 50,000 certified professionals. With an Industry Advisory Panel of experts in academia, fitness, recreation, and wellness, ACE regularly updates their material to incorporate new research in exercise science. Cost: $316 - $702.

• The American College of Sports Medicine (ACSM) has been one of the largest organizations in sports medicine and exercise science since 1954. With more than 25,000 fitness professionals certified in 44 countries, ACSM establishes the exercise guidelines that many other certifications use for testing. Cost: $129 - $375.

• The National Academy of Sports Medicine (NASM) has programs for both novice trainers and seasoned professionals and requires trainers to have comprehensive knowledge of human movement, anatomy, physiology, functional assessment (overhead squat test, anyone?), and program design. Cost: $599 - $799.

• The National Strength and Conditioning Association (NSCA) serves nearly 30,000 members in 52 countries. Founded in 1978, NSCA was the first certification to boast an NCCA accreditation. Their NSCA-CPT certification focuses on skills necessary to train everyone from athletes to couch potatoes to individuals with special needs. Cost: $235 - $420.

Ready, Set, Go! — Your Action Plan

If the goal is to train at a particular health facility, it’s helpful to ask the fitness manager which certifications their club prefers. And some organizations like CrossFit make it relatively easy and inexpensive for trainers to open their own facilities. Before setting up shop, be sure to the research. Opening a new facility requires getting insured for fitness training, a process with its own costs and complications that vary from state to state. New or unproven certifications might not even carry the same respect and/or discounts among insurers.

Other factors to consider are cost and time. More expensive certification packages might cover the cost of the exam, textbook, study guides, DVDs, and live workshops, while others may only cover the exam. From the date of purchase, most associations allow between three months and one year to study, schedule, and complete the exam. So don’t expect to pass after a brief cram session (and beware of too many all-nighter study sessions).

Have tips on how to get through the process from personal experience? Share them in the comments below!

Originally posted April 2011. Updated May 2012.